For any nursing mother out there you may from time to time get a plugged duct. There is a lot of information out there on the internet about this and a good resource for me has been kellymom.com.
This website has some basic information about mastitis vs plugged ducts. So you can go read up on it for yourself if you're having any issues.
For me what I found useful was to use a WARM compress before nursing while massaging the lump toward the nipple and after nursing if the lump was still there to use a cold compress and continue massaging. This with frequent nursing/pumping usually got the duct unplugged. I also could take some ibuprofen as well to help with the pain and get the blood flow circulating better.
